ATI 1900 will not give you more then 6 800x600 using two triple head 2 go , witch is sucks for me
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Using ATI radeon 1900 xt , you can get max movie size of 4096x2048 .

I don't think it's possible on the 7300 ( just 256 vram )

I have no idea a out the Nvidia Quadro FX ... personally I'll not spend that money . infact I didn't